Conventionally, in the manufacturing process of automobiles, a suspension assembly has been attached to the body.
The suspension assembly is assembled by connecting the lower end side of a pair of left and right dampers of a front side or rear side with a sub-frame. In addition, a pair of damper housings in which the pair of dampers is accommodated is formed in the body. An upper end side of the pair of dampers is accommodated in each of the pair of damper housings and is supported by attaching such a suspension assembly to the body.
Herein, variability occurs in the position of the body; therefore, it is necessary to measure the displacement amount of the position of the body. Therefore, with a hole formed in the body set as a measurement point, this suspension assembly is attached to the body by measuring the displacement amount from a reference position of this measurement point, and correcting the movement of a robot that has been taught in advance.
Incidentally, although the displacement amount in an in-plane direction of the photographed image, i.e. the displacement amount in a direction intersecting a photographing direction, can be measured with high precision with the special characteristics of a CCD camera, it is difficult to measure the displacement amount in the photographing direction with high precision thereby.
Therefore, in order to measure the distance in the photographing direction with high precision, a laser distance sensor has been provided and the displacement amount in the photographing direction at a measurement point of the body has been measured by this laser distance sensor, after which the focal length of the CCD camera has been corrected based on this displacement amount measured, and the displacement amount in a direction intersecting the photographing direction at the measurement point of the body has been measured by this CCD camera (refer to Patent Document 1).
In addition, high precision has been demanded in attachment of suspension assemblies to bodies because, if the attachment position of the suspension assembly shifts from the reference position, a difference in left and right camber angles arises.
Therefore, a method is shown in Patent Document 2, for example, for suspension assembly positioning in which the object is to improve the attachment precision of the suspension assembly. With this positioning method, the center position of the body and the center position of the suspension assembly are calculated based on a detection signal from a plurality of distance sensors, and the position of the suspension assembly is adjusted so that these center positions match.
After the position of the suspension assembly has been adjusted in the above such way, the suspension assembly is fixed to the body by tightening bolts provided at an upper end side of the pair of dampers.
In addition, the suspension assembly is fixed to the body by tightening bolts of a plurality of locations. In this case, at each tightening locations, a dedicated nut runner (refer to Patent Document 3) is arranged, respectively.
However, if a dedicated nut runner is provided to each tightening location, in a case of tightening a tightening location at a position that differs for each model, displacement will arise between the arrangement locations of the nut runners and the tightening locations of the suspension assembly. In such a case, conventionally, it has been compensated for by providing in advance a jig to correct these positional displacements on a mounting stand for the suspension assembly, and tightening via this jig.
Patent Document 1: Republication of Internal Publication No. WO 97/24206
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2007-69826
Patent Document 3: Japanese Unexamined Patent Application Publication No. 2007-216789
Patent Document 3: Japanese Unexamined Patent Application Publication No. H9-66425